A fuel-air mixture is generated in the combustion chamber by means of a fuel pump, a combustion air blower, and, e.g., a fuel evaporator. During the combustion of the mixture, the thermal energy is released by a heat exchanger surrounding the combustion chamber to the heat carrier, which is part of a heat carrier circuit.
Vehicle heaters should have a very compact design and meet a high standard in terms of operating safety.
One special problem related to the usual vehicle heaters is the bleeding of the pump circulating the heat carrier, e.g., water, in the heat carrier circuit, Air originating from the filling of the heat carrier circuit must be prevented from collecting or remaining within the pump chamber of the pump part, not only to avoid undesired noises during the operation, but especially to guarantee the desired throughput of the pump. The pump can be driven electrically by a pump motor.
In the usual vehicle heaters, the water pump has hitherto been arranged under the heat exchanger and consequently practically in the deepest area of the entire water circuit. The consequence of this was that air bubbles that may be present in the area of the pump automatically rose up, so that they did not cause any interference at a higher point of the water circuit. In view of the problem of the generation of air bubbles in the pump area, the water pumps were hitherto intentionally arranged under or next to the heat exchanger in order to guarantee the escape of the air bubbles due to this special installation position.